The demand for improved energy storage devices has increased steadily with the advent of new techniques utilizing batteries as power sources. A particularly large application is batteries for man-portable electronic equipment, where expense, reliability, lightweight, durability and high energy density are critical features. For applications with large loads, rechargeable batteries are often used and lithium systems offer the potential for both high energy and light weight. An important objective in developing a practical rechargeable lithium battery for this application is to provide an inexpensive, high energy material with excellent cycle-life and rate capabilities for use as the cathode.
The class of lithium intercalating transition metal oxides are particularly attractive for this purpose because of their tendency to possess high energy content. However, the known oxides are either expensive to prepare as is the case with the vanadium oxides or they are electronic insulators thereby preventing their use for high battery current applications. Another difficulty with transition metal oxides, especially V.sub.2 O.sub.5 is susceptibility to over-discharge which results in structural rearrangement and severe losses in cell capacity.